The Effects of Preprocessing Strategies for Pediatric Cochlear Implant Recipients

Background: Cochlear implants (CIs) have been shown to improve children’s speech recognition over traditional amplification when severe-to-profound sensorineural hearing loss is present. Despite improvements, understanding speech at low-level intensities or in the presence of background noise remains difficult. In an effort to improve speech understanding in challenging environments, Cochlear Ltd. offers preprocessing strategies that apply various algorithms before mapping the signal to the internal array. Two of these strategies include Autosensitivity Control™ (ASC) and Adaptive Dynamic Range Optimization (ADRO^®). Based on the previous research, the manufacturer’s default preprocessing strategy for pediatrics’ everyday programs combines ASC + ADRO^®.

Purpose: The purpose of this study is to compare pediatric speech perception performance across various preprocessing strategies while applying a specific programming protocol using increased threshold levels to ensure access to very low-level sounds.

Research Design: This was a prospective, cross-sectional, observational study. Participants completed speech perception tasks in four preprocessing conditions: no preprocessing, ADRO^®, ASC, and ASC + ADRO^®.

Study Sample: Eleven pediatric Cochlear Ltd. CI users were recruited: six bilateral, one unilateral, and four bimodal.

Intervention: Four programs, with the participants’ everyday map, were loaded into the processor with different preprocessing strategies applied in each of the four programs: no preprocessing, ADRO^®, ASC, and ASC + ADRO^®.

Data Collection and Analysis: Participants repeated consonant–nucleus–consonant (CNC) words presented at 50 and 70 dB SPL in quiet and Hearing in Noise Test (HINT) sentences presented adaptively with competing R-Space^TM noise at 60 and 70 dB SPL. Each measure was completed as participants listened with each of the four preprocessing strategies listed above. Test order and conditions were randomized. A repeated-measures analysis of was used to compare each preprocessing strategy for the group. Critical differences were used to determine significant score differences between each preprocessing strategy for individual participants.

Results: For CNC words presented at 50 dB SPL, the group data revealed significantly better scores using ASC + ADRO^® compared to all other preprocessing conditions while ASC resulted in poorer scores compared to ADRO^® and ASC + ADRO^®. Group data for HINT sentences presented in 70 dB SPL of R-Space^TM noise revealed significantly improved scores using ASC and ASC + ADRO^® compared to no preprocessing, with ASC + ADRO^® scores being better than ADRO^® alone scores. Group data for CNC words presented at 70 dB SPL and adaptive HINT sentences presented in 60 dB SPL of R-Space^TM noise showed no significant difference among conditions. Individual data showed that the preprocessing strategy yielding the best scores varied across measures and participants.

Conclusions: Group data reveal an advantage with ASC + ADRO^® for speech perception presented at lower levels and in higher levels of background noise. Individual data revealed that the optimal preprocessing strategy varied among participants, indicating that a variety of preprocessing strategies should be explored for each CI user considering his or her performance in challenging listening environments.

Key Words

ADRO® - ASC - cochlear implant - preprocessing strategies - speech perception